The evolution of cognitive abilities in marine animals: a hypothesis based on insights about cognition gene polymorphisms in Coelocanths and lungfish

Both coelacanths and lungfish have fossil evidence dating back 400 million years, placing them at a critical evolutionary juncture when marine animals transitioned to terrestrial environments. An intriguing question lies in the extent to which their cognitive abilities had evolved before they crawled onto land. While no fossil DNA exist for extinct coelacanths or lungfish, studies on their extant species offer clues. Notably, the biological traits of coelacanths and lungfish have been remarkably stable over the past 70 million years, suggesting that some genomic regions in their genomic sequences possess exceptional stability. This raises the possibility of inferring their cognition gene polymorphism patterns (CGPPs) and evolutionary positioning through genomic analyses of modern samples. By employing 471 whole-genome sequence samples, including archaic humans (Neanderthals, Denisovans and more), modern humans, other vertebrates (fish, amphibians, reptiles, birds, rodents, mammals) plus four coelacanth and three lungfish samples, together with 18 human cognition-related genes and their total of 223 SNVs (Single-Nucleotide Variations),comparative analyses revealed that the CGPPs of both coelacanths and lungfish are evolutionarily closer to those of archaic humans than those of most other animal groups. The CGPP appears to occupy an evolutionary inflection point, bridging diverse animal lineages to archaic hominoids. Our observational results suggest a hypothesis (to be validated in the future) that the genetic architecture underlying human cognitionseemsto have beenestablished during the evolutionary stage of fish, predating the emergence of tetrapods.